Vitamin A and its derivatives (=retinols), such as typically vitamin A and vitamin A acetate or the like, have heretofore been known as ingredients effective for prevention or remedy for skin keratosis and for prevention or recovery of skin aging, and are incorporated as active ingredients in external preparations for skin.
However, vitamin A and its derivatives are unstable and are readily denatured by the influence of light, air, heat, metal ions and the like thereon. Accordingly, external preparations for skin with such vitamin A and its derivatives incorporated therein have a problem in the stability with the passage of time thereof. Heretofore, for solving the problems, there has been reported a technique of incorporating an oil-soluble antioxidant thereinto. For example, JP 11-228377A (Patent Reference 1) discloses an oil in water emulsion composition containing a vitamin A fatty acid ester, an oil-soluble antioxidant, an amphiphilic substance, and a hydrophilic nonionic surfactant in a specific blend ratio. JP 2005-104962A (Patent Reference 2) discloses an external preparation for skin containing vitamin and/or its derivative, a chemical having a superoxide removal rate of at least 75% and an oil-soluble antioxidant.
The invention described in Patent Reference 1 exhibits an excellent effect for stable incorporation of vitamin A and its derivatives, however, it has made no investigation for the feeling in use (skin familiarity, feeling of efficacy after application) in particular. Patent Reference 2 also does not have a description relating to the effect of feeling in use.
JP 2005-320263A (Patent Reference 3) discloses an oil in water emulsion cosmetic composition for skin, especially a cream-type one for which the feeling in use such as fittability, permeability and the like, is aspired for; however, the patent publication does neither describe nor suggest stable storage of vitamin A and its derivatives.